Cam gear for internal combustion engines



Oct. 9, 1934. A. KREIDLER 1,976,236

CAM GEAR FOR INTERNAL COMBUSTION ENGINES A Filed larch 22, 1932 2Sheets-Sheet l Z? flreiquew Jzwezziar:

Oct. 9, 1934. KREIDLER 1,976,286

CAM GEAR FOR INTERNAL COMBUSTION ENGINES Filed March 22, 1932 2Sheets-Sheet 2 Registered Oct. 9, 1934 UNITED STATES CAM GEAR FORINTERNAL COMBUSTION ENGINES Anton Kreidler, Stuttgart, GermanyApplication March 22,1932, Serial No. 600,517 In Austria April 15, 19312 Claims.

The invention relates to internal combustion engines (for I exampleexplosion-Diesel twostroke cycle or multi-fstroke cycle engines) inwhich the piston movement is converted into the rotary motion of thedriving shaft not by crank gear but by cam gear.

It is a particular advantage of cam gear that the course of the pistonmovement is not confined to that determined bythe crank gear, but thatit is possible by suitable configuration of the cam tracks to move thepiston as desired during one revolution of the engine shaft, forexample, to accelerate the movement of the piston, to retard it or eventemporarily to stop it entirely.

The invention utilizes this advantage, in such internal combustionengines, in which the fuel is supplied during or before the compressionof the air for combustion for the purpose of securing spontaneousignition of the fuel mixture at the correct instant instead of byelectrical ignition or by the incandescent method of ignition. This iseffected by appropriate configuration of the cam track (compression camcurve) provided on the cam, which cam track effects the compression ofthe mixture. This compression cam curve is so constructed according tothe invention that the piston moved thereby first of all precompressesthe fuel mixture to an extentsuch that spontaneous ignition does not yetoccur, while the compression curve rises very steeply towards its end,thereby effecting 'such rapid and high compression of the fuel mixturethat spontaneous ignition of the latter occurs.

The new type of compression process just described is also applicable inthe case of a Diesel engine in which the fuel is only admitted at theend of the high compression of the fresh air. In this case, fresh air isprecompressed. first of all, but the rapid and high compression of thefresh air occurring towards the end of the compression curve then bringsthe said air intensively to a state of incandescence, hence considerablypromoting the spontaneous ignition of the fuel which is now admitted.

Whereas in crank engines the piston only slowly increases compressiontowards the end of thecompression stroke, and the resulting heat ofcompression is partly absorbed unused by the cylinder walls, the latteroccurrence is considerably diminished according to the invention by therapid high compression at the end of the compression stroke.

Since, in the case of the cam gear, the transition from the compressioncurve to the working curve is very rapid, there is the disadvantage,particularly in the case of high speed engines, that this change ofcurve proceeds more rapidly than the time taken for combustion todevelop Consequently, the working piston and hence the working curve isnot under the desired working pressure from the beginning of the saidcurve. This disadvantage is obviated according to the invention byproviding between the end of the compression curve and the beginning ofthe working curve on the cam a substantially rectilinear transitionportion which practically stops the working piston until the combustioninitiated by the spontaneous ignition has been fully developed. Thisarrangement corresponds to the known pro-ignition in internal combustionengines. 7

One' constructional example of a cam gear according to the invention asapplied to an internal combustion engine is shown in the accom-' panyingdrawings, wherein:

Figure- 1 shows in axial section the cam gear applied to amulti-cylinder tw -stroke cycle internal combustion engine with pistonsrunning counter to one another.

Figure 2shows on a larger scale a compression and a working curve indevelopment after and the position of the working piston spontaneousignition of the fuel has occurred.

Referring to the drawings, 1 and 2 are the pistons, 3 is the cam mountedon the driving shaft 4. The pistons run on the tracks of the said cam bymeans of rollers '7 or slide shoes. The admission and exhaust ports areshown at 5 and 6 respectively.

In Figure 2, the compression curve is shown at 15, 16 being its steeplyrising portion at the end, d-e the connection portion betweencompression and working curve and 1'? the working curve.

In Figure 1, the pistons 1 and 2 are at the instant at which spontaneousignition has occurred. (See also Figure 2.) The pistons in movingoutwardly run along the connecting distance H and by their pressure uponthe steep working curve 17 situated opposite them set the driving shaft4 in rotation. The piston. 1, now 1a passes the exhaust port 6 anduncovers it for the most part, and the combustion residues escape.Piston 2 at this instant still covers the inlet. Both pistons movefurther. Piston 1 passes the exhaust port and piston 2 uncovers theinlet port, so that the fresh gas mixture or the scavenging air canenter the cylinder. During the further course of the rotation of thecam, pistol 1 closes the exhaust 6 and then piston 2 closes the inlet 5.Both pistons are now on the compression curves 15, Fig. 2, which movethem towards the middle of the cylinder to compress the contents of thecylinder. On passing over the steep end portion 16 of the compressioncurve, a rapid compression of the fuel mixture takes place incooperation with the piston 2, which is rapidly moved forward at thesame time from the other end, thereby eflecting spontaneous ignition ofthe fuel mixture, whereupon the working of the pistons is repeated inthe manner described in the foregoing.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, I declare thatwhat I claim is: p

1. A piston operated cam gear for internal combustion engines of theDiesel two-stroke cycle and multi-stroke cycle type including a camtrack having compression and working portions,

the part of the compression portion immediately adjacent the workingportion having a steeper inclination than the remaining compressionportion whereby to effect a sudden increase of pressure at a more rapidrate than at the beginning of the compression period.

2. A piston operated cam gear for internal vided with a substantiallyrectilinear transition portion between the compression and workingportions.

ANTON KRElDLER.

